I bought a tank and four fish last week for my sons birthday.The black one died during the night.I am new to this and wonder can any one help we changed the water in the tank on thurs less than a week after getting them because it was gone very cloudy on friday he was acting very strange he just stayed at the top of the tank as if he was trying to get some air.he died during the night and my 8 year old son is very upset.I would love if some one could advise as to what went wrong.cause im worried about others now

Did you cycle your tank before putting in the new fish? Many times new goldfish owners just fill 'er up, turn on the filter, and pop in a bunch of fish at once. What they don't realize is at this time (usually for the first 1-3 weeks) an invisible war is going on. Good bacteria is fighting the bad bacteria to establish the colony, and at this time water parameters are in complete chaos. Cloudy water is typically a sign of this happening, usually referred to as a bacteria bloom. These ever changing water circumstances are very dangerous to goldfish, especially during an ammonia or nitrite spike. Before adding in new fish for a while, get your water tested once a week for the first few weeks at your local pet store (most provide free water testing for their customers) or do it yourself by buying a tester kit. Running the tank for a while to let bacteria colonies establish is referred to as the "fish-less cycle". Otherwise, you can end up with a bunch of problems, such as "new tank syndrome" which includes a symptoms of loss of appetite, black smudges (ammonia burns) on body, and usually sudden death.

Another cause of fish deaths early on could be that you are overcrowding. What size is your tank? For 4 goldfish you should have a 30-40 gallon tank (rule of thumb is for every 10 gallons you should have 1 fish, though sometimes with a lot of filtration and water changes you can squeeze them in). Overcrowding mixed with poor filtration mixed with unpredictable water parameters is a recipe for disaster.

Also, what kind of water conditioner are you using when you make water changes? You should be using something that removes chlorine and chlorimines (like Aquasafe) if you are on well water, and if you are on city water you should use something (like Amquel+) that takes out ammonia, nitrites, and if you are on city water. What many first-time pet owners don't realize is putting a fish in water that is treated without proper treatment is also deadly to fish.

thats a great help,yes i just filled the tank and put the fish in as i am new to this.wouldn ye think the pet shop would have explained all this to me when i bought them.I will bring some tank water up to shop for testing tomorrow.The other 3 fish seem fine so fingers crossed.Thanks for your help

Goldiegirl pretty much covered it all But I would like to emphasize the importance of proper stocking of your tank. You can't think that the fish are "still so small!" because goldfish tend to grow very fast, and very big. They also produce a lot of ammonia, so you need to make sure that there's enough water for each fish to swim in, and so that the ammonia and waste products won't be too concentrated in the tank.

Also, remember to buy a water conditioner and a test kit! It's important that you test for ammonia every day for the first two weeks, later for nitrite and finally nitrate. Do water changes whenever the levels get too high, about half would be good. Make sure you have a good biological filter to deal with the fish waste as well! It should turn at least 5 times the tank volume per hour.

All well covered by Nossie and Goldiegirl, but I still like to put my "cents" in as well.

First of all - as you mentioned too - what kind of petshop is this where you were sold the fish and the tank without any advice that the tank must cycle first for at least 3 weeks before you can add fish, especialy if you haven't got already some established filtermedia from another cycled tank to speed this cycle up. Those people there are only interested in the almighty dollar, but not in the fishies welfare, hapiness.In this case I'd go there and ask for the manager and ask for money back.

Second; look for another reputable pet shop.

Third: Very important to get beneficial bacteria and a waterconditioner ( I use "Stability" and "Prime" both from Seachem )Stability is the beneficial bacteria to avoid the "First Tank Syndrome" and "Prime" removes Chlorine, Chloramine, etc from tap waterYou also will need a test kit to test the water chemistry on a regular basis: API MasterTestKit for Freshwater. It contains liquid tests for Ammonia, Nitrite, Nitrate and pH (low and high range)

The Nitrogen cycle was explained before in other posts, I will find the link to it and post it on here too.

When you set the tank up you should have a good filter too, best with 3 or more ( better 5 )times the capacity as the tank volume is. An airstone and a pump to provide fresh air and helps oxygenate the water.Nice thick layer of gravel where you can plant LIVE plants, not artificial ones as they don't do nothing for the fishes.Aquariumlight.Chose a good place for the tank, away from windows, aircondition, direct sunlight.Goldfishfood: chose a varied diet, different high quality brands like Sera, Hikari, Tetra, OmegaOne, frozen bloodorms. They also eat strawberries, watermelon, zucchini, cucumbers, broccoli, sweet orange pulp and frozen, thawed, shelled peas, all cut in small pieces.

Now when you set up the tank and it is running you can start the cycle with adding fishfood to the water, but no fish if possible. Add Stability daily according to instructions. After 4 days you can add the first fish, just like it is explained on the bottle.

HOW BIG IS YOUR TANK?

Hope this helps, don't be discouraged, it isn't difficult. You and your family will be rewarded many, many times with happy, healty and thriving fishies. They will also show their love to you after a while and giggle,wiggle for you.

First you should remove the left over food as it pollutes the water.... and with this we can start and talk about the Nitrogen Cycle and cycling the tank ... may sound scary but it is easy...

OK, lets get started:1. Fish produce waste with their poop, etc. Plants decompose ( dead leaves ) uneaten food decomposes. All those produce Ammonia which is highly toxic to our fish. It is like swimming in sewerage.2. to break Ammonia down we need beneficial bacteria. They brake it down into Nitrite which is still toxic to fish.3. to break Nitrite down we need beneficial bacteria again which brake it down to Nitrate ( which is only toxic to fish in high concentration )

To control the cycle there are test kits available. I use the API Master TestKit for freshwater it contains all tests for Ammonia, Nitrite, Nitrate and pH. If you start cycling a tank ( planted with some live plants and add beneficial bacteria and some fish food but no fish ) Your tankwater will go a bit cloudy, which is normal. It means the beneficial bacteria try to find their home.

Ammonia will show first. After a few days it will start to go down and also Nitrites will spike. You will need to do some waterchanges, about 50 % but don't clean the filter as most bacteria establish in there and in the gravel. Keep adding beneficial bacteria, also a water conditioner every time you do those waterchanges.After another while Ammonia will go down to 0 ppm and Nitrite will go down and Nitrates will show up.

A tank is cycled when Ammonia and Nitrites are both 0 ppm ( parts per million ) and Nitrate shoudn't be higher than 20 ppm, ideal between 5 -10 ppm. At this point it is safe to introduce the fish: one at the time for beginners

Now, here is where the plants "function" kicks in as well. Plants love Nitrates to grow. They also use up Carbondioxide which fishes produce. They need it for their Photosynthesis and they return Oxygen into the water... for fishes to breath

This is the basics how this small ecosystem works in the tank.

Hope it doesn't sound scary.It is really not hard to test waterquality and do waterchanges.

According to Spaz not eating it is because he suffers in the bowl and gasps for air. You also can try another type of food, as fish love different diets. Also feed only very, very little. If there is some food left after 5 min, remove it. For starters get some hornworth he may like to nibble on this plant. And a pump and an airstone to put in the bowl. Test the water and change 50 % of the water daily if necessary. Add some beneficial bacteria.

In a way, it looks a lot like a koi, and still the body seems a bit too round?But maybe it's a wild carp or something I've seen some in the pet shop that look so much like this one! And they're simply labeled as "carps". (They've had koi too, but then they were actually labeled as "koi")